Other Real Estate Owned, Net - Carrying Value of Properties Included in Other Real Estate Owned (OREO) (Detail) $ in Thousands	Sep. 30, 2018 USD ($) Property	Dec. 31, 2017 USD ($) Property
Real Estate Properties [Line Items]
No. of Properties | Property	25	29
Carrying Value | $	$ 3,663	$ 4,284	[1]
Residential
Real Estate Properties [Line Items]
No. of Properties | Property	4	5
Carrying Value | $	$ 1,240	$ 443
Land
Real Estate Properties [Line Items]
No. of Properties | Property	18	20
Carrying Value | $	$ 1,896	$ 3,223
Commercial properties
Real Estate Properties [Line Items]
No. of Properties | Property	3	4
Carrying Value | $	$ 527	$ 618

[1] Derived from audited December 31, 2017 Consolidated Financial Statements.